Hypoplastic Left Heart Syndrome (HLHS) in Children

What is hypoplastic left heart syndrome in children?

Hypoplastic left heart syndrome (HLHS) is a group of defects of the heart and large blood vessels. A child is born with this condition (congenital heart defect). It occurs when part of the heart doesn't develop as it should during the first 8 weeks of pregnancy.

In hypoplastic left heart syndrome, most of the left side of the heart is small and underdeveloped. These structures are usually affected:

Mitral valve. This valve controls blood flow between the left atrium and left ventricle.

Left ventricle. This is the lower left chamber of the heart. It pumps blood to the body.

Aortic valve. This valve controls blood flow from the left ventricle into the aorta, and then to the body.

Aorta. This is the large artery leading from the left ventricle to the body.

The left ventricle is normally very strong so it can pump blood to the body. When it is small and poorly developed, it can't pump any or enough blood out to the body. For this reason, an infant with hypoplastic left heart syndrome will not live long without surgery to fix the defect.

What causes hypoplastic left heart syndrome in a child?

Some congenital heart defects occur more often in certain families (genetic defects).

In many children, HLHS occurs by chance. There is no clear reason for its development.

What are the symptoms of hypoplastic left heart syndrome in a child?

Babies with HLHS usually get symptoms shortly after birth:

Blue color of the skin, lips, and nails (cyanosis)

Pale skin

Sweaty, clammy, or cool skin

Trouble breathing

Fast heart rate

Cold feet

Poor pulses in the feet

Poor feeding

The symptoms of hypoplastic left heart syndrome may look like other health conditions and heart problems. Make sure your child sees his or her healthcare provider for a diagnosis.

How is hypoplastic left heart syndrome diagnosed in a child?

In many cases, hypoplastic left heart syndrome can be diagnosed with an ultrasound while the fetus is still in the womb (uterus). After birth, you or your healthcare provider may notice that your baby seems limp or listless, has trouble breathing, or has a blue color to his or her skin, lips, or nails. Your child will need to see a pediatric cardiologist for a diagnosis. This is a doctor with special training to treat heart problems in children.

The cardiologist will examine your baby, listen to his or her heart and lungs, and make other observations. Testing for congenital heart disease varies. Your child may have these tests:

Chest X-ray. A chest X-ray may show problems that show up with hypoplastic left heart syndrome.

Echocardiogram (echo). An echo uses sound waves to make moving pictures of the heart and heart valves. Children with HLHS are almost always diagnosed by echocardiography.

How is hypoplastic left heart syndrome treated in a child?

Your baby will most likely be cared for in the neonatal intensive care unit (NICU). At first, he or she may be placed on oxygen, and possibly even on a ventilator. This is to help with breathing. Your child may get IV medicine (delivered into a vein). The medicine helps the heart and lungs work.

In the majority of cases, surgery is used to treat HLHS. Your baby’s cardiologist and cardiac surgeon will explain the risks and benefits. One treatment is a heart transplant. But it is very difficult to find a donor heart for a baby. For this reason, transplant is not often done as the first-line treatment.

Surgery typically involves a series of 3 surgeries. In this very complex treatment, the surgeon redirects blood flow to the lungs and the body with several connections. The surgery is done in stages. The first surgery is done shortly after birth. The second is done at about 3 to 6 months of age. The third is done at about 18 months to 4 years of age.

Another option for treatment of HLHS is a combination of surgery and cardiac catheterization. This is called a hybrid procedure. It accomplishes the goal of the first surgery without the need for placing your child on a heart-lung machine. This procedure is typically reserved for children who are at high risk (such as premature, low birth weight, and organ dysfunction).

After the surgery, babies will return to the intensive care unit (ICU) to be closely watched. After the first surgery, you can expect your child to be in the hospital for 3 to 4 weeks. When your child is well enough to go home, the healthcare provider may recommend pain medicine such as acetaminophen or ibuprofen to keep your child comfortable. Your child's healthcare provider will discuss pain control before your child goes home.

If any special treatments are to be given at home, the nursing staff will make sure that you or a home health agency are able to provide them.

You may get other instructions from your child's healthcare providers and the hospital staff.

How can I help my child live with hypoplastic left heart syndrome?

Without surgery, most babies with HLHS will not live longer than a few days or weeks.

The first stage of the surgery has the highest risk for complications and death. Some special treatment centers that do many of these procedures have higher survival rates than centers where fewer procedures are done. Survival rates are higher with the second and third stages of surgery.

Babies and children who have the staged surgeries will need special care and treatment to support growth and development. These children often have physical developmental delays and will likely need extra support.

In the long term, these children have an increased risk for complications such as heart failure and heart rhythm problems. They are also at risk for digestive and liver problems.

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